SPOJ-LCS2 sam

LCS2.cpp

#include <cstdio>
#include <cstring>
#include <algorithm>
const int N = 100000 * 2 + 9;
char s[N];
struct SAM
{
    int l[N],fa[N],ch[N][26],cnt,len,last,b[N],t[N],mnl[N],cl[N];
    void init()
    {
        cnt = last = 1; len = 0;
        memset(ch[1],0,sizeof ch[1]);
    }
    void add(int c)
    {
        int np = ++cnt,p = last; last = np;
        l[np] = ++len; memset(ch[np],0,sizeof ch[np]);
        for (; p && !ch[p][c]; p = fa[p]) ch[p][c] = np;
        if (!p) fa[np] = 1;
        else {
            int q = ch[p][c];
            if (l[p] + 1 == l[q]) fa[np] = q;
            else {
                int nq = ++cnt;
                l[nq] = l[p] + 1;
                memcpy(ch[nq],ch[q],sizeof ch[q]);
                fa[nq] = fa[q];
                fa[q] = fa[np] = nq;
                for (; ch[p][c] == q; p = fa[p]) ch[p][c] = nq;
            }
        }
    }
    void build()
    {
        scanf("%s",s);
        init();
        for (char *c = s; *c; ++c) add(*c - 'a');
        for (int i = 1; i <= len; ++i) b[i] = 0;
        for (int i = 1; i <= cnt; ++i) ++b[l[i]];
        for (int i = 1; i <= len; ++i) b[i] += b[i - 1];
        for (int i = 1; i <= cnt; ++i) t[b[l[i]]--] = i;
        for (int i = 1; i <= cnt; ++i) mnl[i] = l[i];
    }
    void solve()
    {
        while (~scanf("%s",s)) {
            for (int i = 1; i <= cnt; ++i) cl[i] = 0;
            int p = 1;
            for (char *cc = s; *cc; ++cc) {
                int c = *cc - 'a';
                while (p && !ch[p][c]) p = fa[p];
                if (!p) len = 0,p = 1;
                else {
                    if (len > l[p]) len = l[p]; ++len;
                    p = ch[p][c];
                }
                if (cl[p] < len) cl[p] = len;
            }
            for (int j = cnt; j; --j) {
                int i = t[j];
                if (mnl[i] > cl[i]) mnl[i] = cl[i];
                if (cl[i] && fa[i]) cl[fa[i]] = l[fa[i]];
            }
        }
        int res = 0;
        for (int i = 1; i <= cnt; ++i)
            res = std::max(mnl[i],res);
        printf("%d\n",res);
    }
}sam;
int main()
{
    #ifndef ONLINE_JUDGE
    freopen("LCS2.in","r",stdin);
    freopen("LCS2.out","w",stdout);
    #endif
    sam.build();
    sam.solve();
}